This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-087655, filed Mar. 27, 2000; and No. 2000-087656, filed Mar. 27, 2000, the entire contents of both of which are incorporated herein by reference.
The present invention relates to a magnetic field characteristics evaluation apparatus for evaluating a device for generating a magnetic field, and a measuring method for evaluating the device for generating the magnetic field. More particularly, it relates to a magnetic field characteristic evaluation apparatus for specifying a portion for generating a magnetic field of a magnetic head as the device for generating the magnetic field, and a measuring method for specifying the portion for generating the magnetic field.
As a well-known device for generating a magnetic field, a magnetic head is exemplified. The magnetic head is used, for example, in a hard disk drive to magnetically write data into a magnetic disk which rotates as a magnetic recording medium, and to magnetically read data from the magnetic disk. The magnetic head is provided, in its structure, with a magnetic gap as magnetic flux generating portion for generating a reproducing or recording magnetic flux. The magnetic head is usually designed or manufactured in such a manner that the magnetic flux is generated only from the magnetic gap. In some cases, owing to a deficiency in a manufacturing process or a design problem, there is a possibility that a leak magnetic flux is generated from an undesired place other than the magnetic gap. With the miniaturization of the magnetic head, the hard disk drive is structured such that the magnetic head is floatingly disposed above the magnetic disk rotating in a further micro gap. In this hard disk drive, there is a problem that not only the normal magnetic flux from the magnetic gap but also the leak magnetic flux from the undesired place writes data into the magnetic disk, or deletes or rewrites original data. This problem is found out after the magnetic head is incorporated into the hard disk drive, and at this point of time it is evaluated that the magnetic head is a defective product.
With regard to conventional evaluation of the magnetic head, the magnetic head is incorporated into the hard disk drive, and steps for writing and reproducing the data are then implemented. At this time, it is judged or evaluated whether or not the magnetic head is defective. Instead of such a judging or evaluating method, there has been a demand for an apparatus and a method in which even in the case of a miniaturized magnetic head, magnetic recording head characteristics can be evaluated by its surface analysis with a high sensitivity and a high resolution.
An object of the present invention is to provide a magnetic field characteristics evaluation apparatus and a magnetic field characteristics measuring method that can accurately measure a surface configuration (in a word, topography) of a device for generating a magnetic field, and exactly specify a magnetic field generating portion of the magnetic field generating device.
According to the present invention, there is provided a magnetic field characteristics evaluation apparatus having the following characteristic constitution.
The constitution comprises: a setting device configured to selectively set a magnetic field generating member in one of a magnetized state in which a magnetic flux is generated and a non-magnetized state in which no magnetic flux is generated;
a probe, at least partially formed of magnetic material, configured to sense the magnetic field generating member during vibration of the probe;
a displacement detector configured to scan the magnetic field generating member with the probe vibrated and detect a first displacement of the probe in the non-magnetized state and a second displacement of the probe in the magnetized state;
a surface profile measuring circuit configured to measure a surface profile of the magnetic field generating member in the non-magnetized state based on the detected first displacement; and
a magnetic distribution measuring circuit configured to separate the probe from the magnetic field generating member in the magnetized state by a constant distance based on the surface profile measured by the surface profile measuring circuit, and measure a magnetic distribution of the magnetic field generating member based on the detected second displacement.
Moreover, to achieve the objects, according to the present invention, there is provided a magnetic field characteristics evaluation apparatus having the following characteristic constitution.
The constitution comprises: a setting device configured to selectively set a magnetic field generating member in one of a magnetized state in which a magnetic flux is generated and a non-magnetized state in which no magnetic flux is generated;
a probe, at least partially formed of magnetic material, configured to sense the magnetic field generating member during vibration of the probe;
a displacement detector configured to scan the magnetic field generating member with the probe vibrated and detect a first displacement of the probe in the non-magnetized state and a second displacement of the probe in the magnetized state;
a surface profile measuring circuit configured to measure two surface profiles of the magnetic field generating member in corresponding to the non-magnetized state and the magnetized state based on the detected first displacement and second displacement respectively; and
calculating circuit configured to calculate a difference between the surface profile based on the detected first displacement and the surface profile based on the detected second displacement.
Furthermore, to achieve the aforementioned objects, according to the present invention, there is provided a magnetic field characteristics measuring method having the following characteristic constitution.
The magnetic field characteristics measuring method comprises: setting a non-magnetized state in which no magnetic flux is generated from a magnetic field generating member;
scanning the magnetic field generating member with a probe, at least partially formed of magnetic material, that senses the magnetic field generating member during vibration of the probe;
detecting a first displacement of the probe;
measuring a surface profile of the magnetic field generating member in the non-magnetized state based on the detected first displacement;
setting a magnetized state in which the magnetic flux is generated from the magnetic field generating member;
separating the probe from the magnetic field generating member in the magnetized state by a constant distance based on the surface profile;
scanning the magnetic field generating member with the probe vibrated;
detecting a second displacement of the probe; and
measuring a magnetic distribution of the magnetic field generating member based on the detected second displacement.
Moreover, to achieve the objects, according to the present invention, there is provided a magnetic field characteristics measuring method having the following characteristic constitution.
The magnetic field characteristics measuring method comprises: setting a non-magnetized state in which no magnetic flux is generated from a magnetic field generating member;
scanning the magnetic field generating member with a probe, at least partially formed of magnetic material, that senses the magnetic field generating member during vibration of the probe;
detecting a first displacement of the probe;
measuring a first surface profile of the magnetic field generating member in the non-magnetized state based on the detected first displacement;
setting a magnetized state in which the magnetic flux is generated from the magnetic field generating member;
scanning the magnetic field generating member with the probe vibrated;
detecting a second displacement of the probe; and
measuring a second surface profile of the magnetic field generating member in the magnetized state based on the detected second displacement; and
calculating a difference between the first surface profile and the second surface profile.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.